The present invention relates to an actively anchored electrode for electrode catheters. Conventional electrode catheters as used currently with cardiac pacemakers, whether mono- bi- or tri- polar, are anchored by way of a distal electrode consisting substantially in a head or point of conductive material that is hooked into the cardiac muscle and associated directly (via a connection made internally of a protective insulating sheath) to a spiral wound conductive wire returning to one of the pacemaker terminals.
During implantation of the catheter, the surgeon uses a special tool operated from the remote end of the spiral wound conductor to corkscrew the point into the cardiac muscle of the patient, where it remains permanently anchored.
The principal drawback betrayed by these implanted elements stems in effect from the very embodiment of the electrode catheter, whereby the point, being connected directly and electrically to the spiral wound wire, also functions as a cardiac sensing and stimulation terminal; the surface area of such an electrode is therefore of generous proportions, so that the concentration of the stimulation current flowing through the lesion produced in the cardiac muscle by penetration of the point gives rise to a negative secondary phenomenon in the electrical activity of the heart, referred to in technical jargon as a "lesion wave".
Accordingly, the object of the present invention is to overcome the drawback in question by providing an electrode capable on the one hand of allowing a secure penetration and anchorage in muscle tissue, and on the other, of producing electrical contact by way of a conductive surface that is proportioned to the requirements of stimulation, devoid of any traumatizing effect and with a greater stimulation sensitivity, the combined effect of which being to eliminate the "lesion wave".